Few books have both impressed and depressed me in equal measures as much as this one has done. Christopher Coker’s magnificently researched Why War? is many things, but it isn’t a beach read. It demands your constant attention and rewards you for it. The essence of his argument is that war is, in the words of Thucydides, ‘the human thing’. We humans have been inextricably linked with war from the outset and it is this intimate connection with conflict that makes us human.

I must confess, as someone who wasn’t drawn to the idea of marching and being bellowed at in the school cadet corps, that war has never appealed to me. I was hugely relieved not to be called up for national service: the prospect of death on some barren shore was